Dentifrice

ABSTRACT

A dentifrice suitable for removing calculus and preventing the build-up of calculus on tooth enamel which contains strontium edatate and a ricinoleate, which have been found to provide a synergistic effect in both removal of calculus and prevention of its build-up.

This invention relates to dental hygiene and, in particular, provides adentifrice having valuable properties in the removal and prevention ofcalculus.

BACKGROUND OF THE INVENTION

It is known that water-containing dentifrices which include strontiumand sequestering agents such as EDTA are effective in the treatment ofhyper-sensitive dentin, gingivitis and periodontitis, apparently throughthe mechanism of substituting strontium for calcium in the calciumhydroxy apatite of the tooth (Schole et al. U.S. Pat. No. 3,699,221 and3,988,434).

It is also known that ricinoleic acid and various esters and salts whichare surface active agents exhibit a higher contact angle with toothenamel than other surface active agents.

SUMMARY OF THE INVENTION

In accordance with the present invention, a water-containing dentifriceincluding both strontium edatate and a ricinoleate provide a synergisticaction in the removal of calculus from teeth and also in the preventionof its build-up.

It is understood by strontium edatate reference is made to the strontiumchelate of EDTA and preferably the disodium strontium salt of ethylenediamine tetraacetic acid. When strontium edatate is present in anaqueous composition, the strontium is available in ionic form.Generally, the amount of strontium present in the dentrifrice can be upto about 25 wt. % of strontium .[.ion.]. .Iadd.edatate .Iaddend.in thetoothpaste, but much smaller amounts, as low as 2.5 wt. %, areeffective. The strontium edatate can be formed in advance or can beprepared in the dentifrice as a mixture of a water soluble salt of EDTAtogether with a pharmacalogically innocuous water-soluble strontiumsalt, preferably in equivalents such that the pH will remain neutral.

The ricinoleate can be any of the alkali metal salts of ricinoleic acid(d-12-hydroxy-cis-9-octadecenoic acid), but preferably is the sodiumsalt. The amount of the ricinoleate is not particularly critical and canbe as high as 10 wt. %. Amounts as low as 0.1 wt. % are, however, alsoeffective.

The preferred proportions in the water-containing dentifrice are 10% byweight of strontium, calculated as disodium strontium ethylene diaminetetra acetate and 0.5% by weight of ricinoleate, calculated as thesodium salt.

The dentifrice product used should not include any calcium or othermetal, salt or compound, from which any such metal would be sequesteredby, and form the corresponding calcium or other metal chelate with theEDTA salt or chelate residue of the strontium chelate in the product.

In other words, the dentrifice products of the invention should notinclude any of the water-insoluble calcium, magnesium or aluminumcompounds ordinarily incorporated as adjuvant bulk excipients indentrifices, for example, as the abrasive ingredient, such as calciumcarbonate, calcium pyrophosphate, magnesium oxide, aluminum oxide orhydroxide, and the like. So also, tin compounds, e.g., stannous fluorideand stannous chlorofluoride, likewise should be excluded.

In place of the foregoing water-insoluble bulk excipients for abrasiveand other purposes, water-insoluble barium and strontium salts, forexample, barium sulphate, barium carbonate, strontium carbonate andstrontium phosphate can be used. The ricinoleate, being a surface-activewetting agent which is compatible with strontium, generally will obviatethe need of other wetting agents.

The following are examples of several dentrifices in accordance with theinvention.

EXAMPLE 1--TOOTHPASTE

    ______________________________________                                        Disodium Salt                                                                 of Ethylenediamine Tetraacetic Acid                                                                  20      grams                                          Strontium Chloride (6H.sub.2 0)                                                                      20      grams                                          Strontium Carbonate    25      grams                                          Sodium Ricinoleate     0.5     grams                                          Algin                  1       gram                                           Essential Oils (for flavoring)                                                                       1       gram                                           Propylene Glycol       25      grams                                          Alcohol                0.9     gram                                           Water quantity sufficient to make                                                                    100     grams                                          ______________________________________                                    

EXAMPLE 2--TOOTHPASTE

    ______________________________________                                        Strontium Edatate    30        grams                                          Barium Sulfate       30        grams                                          Sodium Ricinoleate   1.0       gram                                           Algin                1         gram                                           Essential Oils (for flavoring)                                                                     1         gram                                           Propylene Glycol     20        grams                                          Alcohol              0.9       gram                                           Water quantity sufficient to make                                                                  100       grams                                          ______________________________________                                    

EXAMPLE 3--TOOTHPASTE

    ______________________________________                                        Strontium Edatate  8.0        grams                                           Strontium Carbonate                                                                              25.0       grams                                           Methyl Salicylate  1.25       grams                                           Water              33         cc                                              Natrosol           1.7        grams                                           Sodium Ricinoleate .1         gram                                            Cpc                .3         gram                                            Sodium Saccharin   1.2        grams                                           Propylene glycol   25         cc                                              Water sufficient to make                                                                         100        grams                                           ______________________________________                                    

EXAMPLE 4-6--TOOTHPASTE

    ______________________________________                                                      Preparation                                                                   4      5      6                                                 ______________________________________                                        Strontium Edatate                                                                             30       20     10     grams                                  Strontium Carbonate                                                                           25.0     25.0   25.0   grams                                  Cetyl pyridinium chloride                                                                     0.5      0.5    0.5    gram                                   Oil of cassia   0.75     0.75   0.75   gram                                   Oil of wintergreen                                                                            1.0      1.0    1.0    gram                                   Propylene glycol                                                                              25.0     25.0   25.0   grams                                  Natrosol        1.7      1.7    1.7    grams                                  Saccharin       1.2      1.2    1.2    grams                                  Sodium Ricinoleate                                                                            1.5      .5     .1     grams                                  Water QSAD to 100 grams                                                       ______________________________________                                    

Strontium edatate is prepared by mixing equimolar amounts of strontiumchloride hexahydrate and disodium ethylene diamine tetraacetic acid inhot distilled water, typically at 70° C., for a period of 20 minutes.The weight of strontium edatate is calculated as disodium strontiumethylene diamine tetraacetate and does not include the chloride present.As the ligand is formed, the two hydrogen ions are released for eachmolecule of Na₂ EDTA which results in a decrease of solution pH fromabout neutral to about 4, indicating the formation of the ligand.Strontium carbonate or other abrasive then is slowly added to themixture and heating and mixing are continued as the strontium carbonateor other abrasive is mixed. When strontium carbonate is used, a reactiontakes place with a visible evolution of carbon dioxide as the vapor.This reaction continues for about three to four hours at 70° C. Themixture is allowed to cool and additional ingredients such as propyleneglycol and the like are added as well as make up water for that lostduring the mixing of the strontium carbonate, Na₂ EDTA and strontiumchloride. In Example 1, an excess of strontium chloride was utilized andhence this is separately stated. In Example 2, barium sulfate wassubstituted for strontium carbonate.

In a preferred alternate method of manufacture, Strontium edetate can bemade by adding Strontium Carbonate to an aqueous solution of DisodiumEDTA at a temperature 70° C.-80° C. The Strontium Carbonate is addedslowly. At the completion of the reaction the pH will be between 7 and 8which is adjusted by adding HCl. The bulk excipient or abrasive, such asInsoluble Metaphosphate (IMP) or Strontium Carbonate is added. Themixture is completed with the addition of Thickening Agent (Natrosol),Humectant (Sorbitol and Glycerine), Surfactant (Sodium Ricinoleate) andflavoring.

EXAMPLE 7

    ______________________________________                                        Liquid Dentrifice                                                             ______________________________________                                        Sodium Ricinoleate   0.5       gram                                           Glycerine            20        grams                                          Oil of cloves        0.3       gram                                           Oil of spearmint     0.3       gram                                           Oil of cassia        0.3       gram                                           Saccharin            0.5       gram                                           Strontium edatate    10        grams                                          Tincture cudbear     0.6       gram                                           Water quantity sufficient to make                                                                  100       cc                                             ______________________________________                                         The alcohol and glycerine are added to one another and stirred together,      and, the ricinoleate then is dissolved in the alcohol and glycerine           solution. The saccharin then is stirred in and also the tincture cudbear      for coloring. Then the stronium edatate (crystalline) is stirred in and       followed by the flavoring ingredients, namely, the oils of cloves,            spearmint, and cassia; and finally the water is added, and the whole is       stirred to uniformity.                                                   

The toothpastes of Examples 1-6 are utilized following a regular dailyroutine preferably twice a day. The liquid dentifrice of Example 7 ispreferably used as a mouthwash and can be diluted in water, as with anyordinary mouthwash, and preferably is used at least twice a day.

I claim:
 1. A water-containing dentifrice consisting essentially of strontium edatate in an amount sufficient to provide from about 2.5 wt. % to about 25 wt. % of strontium .[.ion.]. .Iadd.edatate .Iaddend.and from about 0.1 wt. % to about 10 wt. % of a ricinoleate compound said dentifrice being free from strontium edatate-sequestering Ca, Mg, Al, Sn metal.
 2. A dentrifrice according to claim 1 in which the ricinoleate is sodium ricinoleate.
 3. A method for controlling calculus which comprises applying to the teeth a water-containing dentifrice consisting essentially of strontium edatate in an amount sufficient to provide from about 2.5 wt. % to about 25 wt. % of strontium .[.ion.]. .Iadd.edatate .Iaddend.and about 0.1 wt. % to about 10 wt. % of a ricinoleate said dentifrice being free from strontium edatate-sequestering Ca, Mg, Al, Sn metal. 